Integrated circuits (ICs) are formed on semiconductor wafers, where the wafers are separated into individual dies or chips and the individual chips are then packaged by mounting and wire-bonding the chip on a substrate. Once mounted, the chip is encapsulated to protect it from environmental contaminants. Thus, the packaging process is one of the most critical steps in the IC fabrication process, both from the point of view of cost and of reliability. Unfortunately, even the most carefully packaged IC devices can still experience problems if faults or other weaknesses are present in the individual components, such as the mounting substrate.
One common point of failure is in the power bus traces that are formed on the substrates to facilitate electrical connections to circuit components across the substrate. For example, conductive traces (or “interconnects”) are typically formed throughout the interior of the substrate as the “power pad” connections that provide applied power to circuit components. In addition, other interconnects are typically formed around the periphery of the substrate (e.g., a “power ring”) to provide the ground or reference potential for circuit components. Unfortunately, however, interconnect junctions, where such sets of interconnects join/intersect each other or have sharp turns, are often points of weakness in the packaged device due to “current crowding” at these junctions.
Current crowding results when a flow of electrical current builds up at a certain place along the interconnects, which is typically where sharp angles are present either when a single interconnect changes direction sharply or where multiple interconnects intersect. Since the flow of electrical current typically behaves like a flow of water, such junctions should be designed to promote the flow of current in an effort to reduce or prevent current crowding. In modern devices, holes or slots are typically formed in the junctions to relieve stress on interconnects formed at the periphery of the substrate often caused by manufacturing process. However, these holes/slots often exacerbate the problem of current crowding by causing current flowing into the junction to be deflected in random directions, rather than towards an interconnect. If not deflected in the proper direction, current will begin to crowd in the junction, which may result in an electrical burn-out. In addition, such holes/slots remove conductive area from the interconnect/junction, which reduces the maximum amount of current (i.e., current density) that can be present in the junction before a burn-out occurs. Accordingly, what is needed is an interconnect junction for use on semiconductor substrates that does not suffer from the deficiencies found in the prior art.